Fuel cells have been projected as promising power sources for portable electronic devices, electric vehicles, and other applications due mainly to their non-polluting nature. Of various fuel cell systems, the polymer electrolyte methanol based fuel cell technology such as PEMFC and DMFC (direct membrane fuel cell) have attracted much interest thanks to their high power density and high energy conversion efficiency. The “heart” of a polymer electrolyte membrane based fuel cell is the so called “membrane-electrode assembly” (MEA), which comprises a thin, solid proton conducting polymer membrane having a pair of electrode (i.e. an anode and a cathode) layers with dispersed catalysts on the opposing surfaces of the membrane electrolyte.
The catalyst structure formed in the electrode layers is critical to the performance of the fuel cell and the effective utilization of the catalyst. A good catalyst structure must have good proton conductivity, electrical conductivity, and adequate access of reactant gases to the active sites in the structure as well as removal of the reaction byproducts. Prior art methods of manufacturing electrode catalysts include the colloidal method in which ultrasound is used to form catalyst colloids. While the reported colloidal method is useful, there is still a need in the industry to continue development of catalysts structure with controlled particle size and morphology to improve the performance of the fuel cells and utilization of the catalysts.